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Eryngium foetidum L. is an edible plant widespread in Amazonian cuisine and its leaves have high levels of promising phenolic compounds for the production of extracts to be used as natural antioxidant additives. In this study, the in vitro scavenging capacity of three freeze-dried extracts of E. foetidum leaves, obtained by ultrasound-assisted extraction using green solvents [water (H2O), ethanol (EtOH), and ethanol/water (EtOH/H2O)], was investigated against the most common reactive oxygen species (ROS) and reactive nitrogen species (RNS) generated in both physiological and food systems. Six phenolic compounds were identified, chlorogenic acid (2198, 1816 and 506 μg/g) being the major compound for EtOH/H2O, H2O, and EtOH extracts, respectively. All E. foetidum extracts were efficient in scavenging all the ROS and RNS (IC50 = 45–1000 µg/mL), especially ROS. The EtOH/H2O extract showed the highest contents of phenolic compounds (5781 μg/g) and showed the highest efficiency in scavenging all the reactive species, with high efficiency for O2•− (IC50 = 45 μg/mL), except for ROO•, for which EtOH extract was the most efficient. Therefore, E. foetidum leaf extracts, especially EtOH/H2O, showed high antioxidant potential to be used as natural antioxidants in food formulations and are promising for nutraceuticals products.

Arrabidaea chica, a medicinal plant found in the Amazon rainforest, is a promising source of bioactive compounds which can be used to inhibit oxidative damage in both food and biological systems. In this study, the in vitro scavenging capacity of characterized extracts of A. chica leaves, obtained with green solvents of different polarities [water, ethanol, and ethanol/water (1:1, v/v)] through ultrasound-assisted extraction, was investigated against reactive oxygen (ROS) and nitrogen (RNS) species, namely superoxide anion radicals (O2•−), hydrogen peroxide (H2O2), hypochlorous acid (HOCl), and peroxynitrite anion (ONOO−). The extract obtained with ethanol–water presented about three times more phenolic compound contents (11.8 mg/g) than ethanol and water extracts (3.8 and 3.6 mg/g, respectively), with scutellarein being the major compound (6.76 mg/g). All extracts showed high scavenging efficiency against the tested ROS and RNS, in a concentration-dependent manner with low IC50 values, and the ethanol–water extract was the most effective one. In addition, all the extracts were five times more efficient against ROO• than Trolox. Therefore, the extracts from A. chica leaves exhibited high promising antioxidant potential to be used against oxidative damage in food and physiological systems.